Inking mechanism with adjustment for ductor roll oscillation

ABSTRACT

A dab or ductor roll which oscillates to alternately touch an ink-source roll from which it receives ink and an ink-receiving roll to which it transfers the ink oscillates on a pivotted arm. The axis on which this arm pivots is itself movable relative to the axis of the ink-source and ink-receiving rolls in an arcuate path of the same sense as the curvature of the ink-receiving roll. Thus by adjusting the position of the pivot axis the contact time per oscillation between the dab roll and the inksource roll, and hence the amount of ink transferred, can be adjusted and the ink-source roll can rotate intermittently through constant arcs of rotation.

United States Patent [191 Talg [451 Sept. 25, 1973 1 INKING MECHANISM WITH ADJUSTMENT FOR DUCTOR ROLL OSCILLATION [75] Inventor: Alistair Gordon Taig,Claverham,

and. 7 p e.

[73] I Assignee: Strachan & lTenshaw Limited,

[22] Filed: Aug. 12, 1971 [211 App]. No.: 171,047

[52] US. Cl. 101/350, l0l/D1G. 6

[51] Int. Cl B411 31/14 [58] Field of Search 101/349-352,

DIG. 6, 206-210, 356, 357, 358, 360, 361, 362

[56] References Cited UNITED STATES PATENTS 1,452,043 4/1923 Harrold 625,318 5/1899 Bradford 101/350 1,183,623 5/1916 Blaine 101/350 2,330,359 9/1943 Hill 101/350 2,467,199 4/1949 Faeber 10l/D1G. 6

Primary ExaminerJ. Reed Fisher Attorney-Thomas Cifelli, Jr. et al.

[57] ABSTRACT A dab or ductor roll which oscillates to alternately touch an ink-source roll from which it receives ink and an ink-receiving roll to which it transfers the ink oscillates on a pivotted arm. The axis on which this am pivots is itself movable relative to the axis of the inksource and ink-receiving rolls in an arcuate path of the same sense as the curvature of the ink-receiving roll. Thus by adjusting the position of the pivot axis the contact time per oscillation between the dab roll and the ink-source roll, and hence the amount of ink transferred, can be adjusted and the ink-source roll can rotate intermittently through constant arcs of rotation.

4 Claims, 3 Drawing Figures PATENTED SEP25 I973 SHEET. 1 ll! 2 PATENTED SEP 2 5 I973 SHEET 2 0F 2 INKING MECHANISM WI ADJUSNT FOR DUCTOR ROLL OSCILLATION BACKGROUND OF THE INVENTION This invention relates to ink-feed mechanisms for printing machines.

In printing machines the roll which finally transfers ink to a printing plate on a plate cylinder is to be uniformly supplied with ink at a constant and critically controlled rate.

The ultimate source of ink in the machine is an ink fountain a trough one side of which is formed by a fountain roll. A carefully controlled doctor blade governs the amount of ink carried round the fountain roll. It would seem, theoretically, that the rate of supply of ink to the ink roll could be controlled solely by the setting of the doctor blade and by the speed of rotation of the fountain roll. In point of fact continual rotation of the fountain roll is found to be detrimental to the smooth and uniform issuing of ink from the trough and intermittent rotation if found to be much better. in order to provide for intermittent rotation of the fountain roll but continuous rotation of the ink roll there has been introduced an oscillating roll called a dab or ductor roll which touches first on to the fountain roll and then travels in a direction normal to its own axis of rotation until it touches against an ink roll which is to receive the ink from the fountain'roll via the dab roll. The dab roll is usually pivotally mounted and travels an arc of a circle between where it touches the fountain roll and where it touches the ink roll. Control of the amount of ink transfered at each dab is governed by the the are through which the fountain roll rotates whilst the dab roll is in contact; the greater the arc through which it rotates the wider the stripe of ink which is transferred to the dab roll, so that, for a given speed of the printing machine, the control of the amount of ink transferred was achieved by causing the fountain roll to rotate in differing amounts of arc.

SUMMARY OF THE INVENTION Precise control of ink feed by this method can be difficult and the present invention concerns itself with a different and extremely simple means for controlling the amount of ink transferred by the dab roll at each oscillation.

According to the invention an ink feed mechanism has a dab roll for oscillation to cause alternate dabbing contact with an ink-source roll and an ink-receiving roll, the path of oscillation of the dab roll being variable. Preferably it is mounted on a pivoting arm, the axis of pivotting of the arm being movable in space relative to the axis of rotation of the ink-source and inkreceiving rolls. The pivoting arm is preferably driven in oscillation by a spring loaded lost motion linkage and a constant throw eccentric; then, there is no need to adjust the actual throw imparted to the lever arm when the position in space of the pivot axis of the arm is al tered.

Preferably the pivot axis of the arm is mounted for arcuate movement, for example being supported by a crank lever which is itself pivotally mounted. It is preferred that such an arm, i.e., one which is mounted for arcuate movements of its pivot axis shall be mounted in such a way that the locus of the pivot point of the arm is an arc of the same sense as the surface of the ink roll. Thus any alteration in the position of the pivot axis involves a more critical alteration in the time of contact of the dab roll with the fountain roll than with the ink roll.

A consequence of this arrangement is that the fountain roll may rotate intermittently but may always rotate through a constant arc, and this may be kept large, e.g., it is suitable to rotate the fountain roll in steps of approximately 50 to 60 of rotation. The rotation of the fountain roll may begin and end before or after the beginning or ending respectively of the contact between the fountain roll and the dab roll; control is achieved by varying the time of contact between the rotating fountain roll and the ink roll rather than by varying the amount of rotation of the fountain roll in any one step of rotation. The argument is equally applicable to any ink-source roll (e.g., one which is an inkfeed train from a fountain roll). a

The invention includes also a printing machine incorporating such an ink feed mechanism.

A particular embodiment of the invention will now be described with reference to the accompanying drawings wherein:

FIG. 1 is a diagrammatic side elevation of a unit of a printing machine showing, however, on the portions relevant to the present invention,

FIG. 2 is a detailed side elevation the embodiment of ink feed mechanism and,

FIG. 3 is a plan view of the part of the mechanism shown in FIG. 2.

In FIG. I a unit ll of the printing machine has a plate roll 2 and an impression roll 3, the plate roll being acted on roll 4 for supplying ink amongst others. The roll 4 is supplied from an ink fountain 5 via a dab roll 6 and an ink train 7.

FIG. 2 shows in more detail the ink fountain 5 with its fountain roll 10, ink trough 11 and a doctor blade 12, adjustable by feed screws 31 as to the amount of and distribution of ink allowed to escape from the trough onto the surface of the fountain roll 10'. The fountain roll is driven in intermittent rotation in the sense of the arrow A, suitably in steps of approximately 50 to 60 of rotation, but its arc of rotation while it is actually moving is always constant. Ink is transferred from the surface of the fountain roll 10 to the surface of the ink roll 13, which is the first roll in the ink train 7 by the dab roll 6. This is mounted on a lever arm 14 for reciprocation in the are indicated by arrow C, this are being centred on an axis l5. At its bottom end the arm has a bush 16 with projecting eye 17 through which passes a connecting rod 18 from a ring 19 which slides on the surface of an eccentric 20, best seen in FIG. 3. The eccentric 20 is fast with and driven by a shaft 21. A connecting rod 22 from another eccentric (not shown) on the shaft 21 is linked to the clutch (not shown) causing the intermittent rotation of the fountain roll It).

The eye 17 supports a shoulder 23 which is integral with rod 18. Two washers 24 and 25 being slideable on rod 18 are pressed against the sides of the eye 17 by springs 28 and 29 respectively, thus trapping the shouldered portion 23 of the rod 118 within the eye 17, so that reciprocating movement is communicated to the bush 16 but so that when the arm 14 is strongly hindered from motion there can be lost motion between the arm 14 and the rod 18. Locknuts 26 and 27' permit the adjustment of the pressure exerted by the springs 28 and 29.

The roll 6 is borne in a low-friction bearing arrangement 30 at the end of the arm 14 remote from the bush 16.

Thus the lost motion linkage means that the eccentric 20 may be a constant throw eccentric and does not need accurate adjustment in order to achieve adequate and firm contact between the dab roll and the ink or fountain roll. When the roll 6 is in contact with one or the other the spring 28 or 29 holds the roll 6 in substantially constant pressure with roll 10 or 13 as the case may be.

In order to adjust the amount of ink transferred to the ink roll 13 by the roll 6 the pivot axis 15 is movable in space relative to the rolls l and 13. The axle for the pivoting movement of the arm 14 is provided by a portion 35 of a composite shaft 36 which extends across the width of the mechanism. (There is, of course, a symmetrical arrangement provided at the other axial end of the rolls). The arm 14 is rotatable about the shaft portion 35. The shaft 36 is journalled in a crank lever 37 which is itself made rotatable about an axis 38 by being fast with a shaft 39 which penetrates a side frame 40 of the printing machine. Beyond the side frame 40 of the machine the shaft 39 is driven by a worm and wheel arrangement 41.

As can be seen from consideration of FIG. 2, the effect of driving the worm wheel 41 is to shift the axis of pivotting of the arm along a locus indicated by the at cuate double headed arrow B, which is an arc of circle centred on the axis 38. The axis 38 is the same side of the arm 14 as is the axis of the ink roll 13 (to put it another way, seen from the roll 13 the locus B is concave) so that adjusting movement of the position of the axis 15 is more crucial for contact time of the dab roll with the fountain roll than it is for contact time with the roll 10. The curvature of the locus B and of the roll 13 is in the same sense, seen on the axis of rotation of the roll 6. Clearly as the axis is moved toward the nip between rolls 10 and 13, similarly the roll 6 moves away from the nip and the contact time with the fountain roll 10 and hence the amount of ink transferred per stroke becomes less, without any variation in the arc of rotation of the fountain roll or of the throw of the eccentric. Accurate and critical control of the amount of ink fed can be achieved.

1 claim l. Ink feed mechanism for a printing press compris mg:

an ink source roll,

an ink receiving roll,

and a ductor roll,

said ink source roll and said ink receiving roll having parallel axes of rotation and being spaced apart from each other,

said ductor roll having an axis of rotation parallel to the axes of rotation of said ink receiving roll,

and said ink source roll and being located between said ink receiving roll and said ink source roll,

a pivoted lever construction having a bearing mounted in a first end thereof, said ductor roll being rotatably mounted about said bearing in said pivoted lever construction, the axis of said bearing being located in a permanently predetermined position on said pivoted lever,

a rotatable eccentrically mounted cam having an external circumference,

an annular ring rotatably mounted about the external circumference of said eccentric cam,

a rod rigidly connected to said ring in the principal plane thereof,

a first and a second spring axially mounted about said rod,

a first and a second stopper axially mounted on said rod,

said first stopper being located on the end of the rod proximate to the ring, said second stopper being mounted on the other end of said rod,

a bushing having an aperture journaled therethrough at one end thereof perpendicular to the principal axis of said bushing, said bushing being located on said rod between said first and said second spring, said rod passing slideably through the aperture in said bushing, the other end of said bushing being rotatably mounted in the second end of said pivoted lever construction the axis of rotation of said bushing in said lever being parallel to the axes of rotation of the ductor roll, the ink supply roll and the ink receiving roll,

a first shaft bearing said pivot lever construction between the first and second ends thereof,

the axis of said first shaft being parallel to the aforementioned four axes of rotation,

a crank lever having a first and a second aperture journaled therethrough, said first shaft passing through the first aperture,

a second shaft, one end of said second shaft being fixedly mounted .in said second aperture in said crank lever,

and means to rotate said second shaft, said rotating means being attached to the end of said second shaft other than the end passing through said second aperture, the axes of rotation of said first and said second shafts being parallel to the aforementioned five axes of rotation.

2. The ink feed mechanism as claimed in claim 1 wherein means are provided for intermittently driving the ink source roll in rotation, through a constant arc of rotation during each said intermittent period.

3. The ink feed mechanism as claimed in claim 1 wherein the axes of rotation of the ink receiving roll and of the crank lever respectively are on the same side of the common plane containing the axes of pivotting of the lever and of rotation of the ductor roll.

4. The ink feed mechanism according to claim 3 wherein the axes of rotation of the ductor roller and of pivoting of the lever lie on opposite sides of the plane containing the axes of rotation of the ink source and the ink receiving rolls. 

1. Ink feed mechanism for a printing press comprising: an ink source roll, an ink receiving roll, and a ductor roll, said ink source roll and said ink receiving roll having parallel axes of rotation and being spaced apart from each other, said ductor roll having an axis of rotation parallel to the axes of rotation of said ink receiving roll, and said ink source roll and being located between said ink receiving roll and said ink source roll, a pivoted lever construction having a bearing mounted in a first end thereof, said ductor roll being rotatably mounted about said bearing in said pivoted lever construction, the axis of said bearing being located in a permanently predetermined position on said pivoted lever, a rotatable eccentrically mounted cam having an external circumference, an annular ring rotatably mounted about the external circumference of said eccentric cam, a rod rigidly connected to said ring in the principal plane thereof, a first and a second spring axially mounted about said rod, a first and a second stopper axially mounted on said rod, said first stopper being located on the end of the rod proximate to the ring, said second stopper being mounted on the other end of said rod, a bushing having an aperture journaled therethrough at one end thereof perpendicular to the principal axis of said bushing, said bushing being located on said rod between said first and said second spring, said rod passing slideably through the aperture in said bushing, the other end of said bushing being rotatably mounted in the second end of said pivoted lever construction the axis of rotation of said bushing in said lever being parallel to the axes of rotation of the ductor roll, the ink supply roll and the ink receiving roll, a first shaft bearing said pivot lever construction between the first and second ends thereof, the axis of said first shaft being parallel to the aforementioned four axes of rotation, a crank lever having a first and a second aperture journaled therethrough, said first shaft passing through the first aperture, a second shaft, one end of said second shaft being fixedly mounted in said second aperture in said crank lever, and means to rotate said second shaft, said rotating means being attached to the end of said second shaft other than the end passing through said second aperture, the axes of rotation of said first and said second shafts being parallel to the aforementioned five axes of rotation.
 2. The ink feed mechanism as claimed in claim 1 wherein means are provided for intermittently driving the ink source roll in rotation, through a constant arc of rotation during each said intermittent period.
 3. The ink feed mechanism as claimed in claim 1 wherein the axes of rotation of the ink receiving roll and of the crank lever respectively are on the same side of the common plane containing the axes of pivotting of the lever and of rotation of the ductor roll.
 4. The ink feed mechanism according to claim 3 wherein the axes of rotation of the ductor roller and of pivoting of the lever lie on opposite sides of the plane containing the axes of rotation of the ink source and the ink receiving rolls. 